1. Field of the Invention
The present invention relates to a method for forming a semiconductor structure.
2. Description of the Related Art
For current integrated circuit (IC) processing, controllers, memories, low-voltage (LV) circuits and high-voltage (HV) power devices are integrated into a single chip, referred to as a single-chip system. For example, to handle high voltage and current, double-diffused metal oxide semiconductor (DMOS) transistors, frequently used as conventional power devices, can operate with low on-resistance while sustaining high voltage. Lateral double-diffused metal oxide semiconductor (LDMOS) transistors in particular have a simple structure suitable for incorporation into VLSI logic circuits.
The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of integrated circuit evolution, functional density has generally increased while geometry size has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs.
However, IC processing and manufacturing problems arise when feature sizes continue to decrease. For example, it is more difficult to form a precisely-defined mask layer for a photolithography process.